kls-signatures

JavaScript library that implements BLS signatures with aggregation as in Boneh, Drijvers, Neven 2018, using the relic toolkit for cryptographic primitives (pairings, EC, hashing).

This library is a JavaScript port of the Chik Network's BLS lib. We also have typings, so you can use it with TypeScript too!

Usage

npm i kls-signatures --save # or yarn add kls-signatures

Creating keys and signatures

  var loadBls = require("kls-signatures");
  var BLS = await loadBls();
  
  var seed = Uint8Array.from([
    0,  50, 6,  244, 24,  199, 1,  25,  52,  88,  192,
    19, 18, 12, 89,  6,   220, 18, 102, 58,  209, 82,
    12, 62, 89, 110, 182, 9,   44, 20,  254, 22
  ]);
  
  var sk = BLS.AugSchemeMPL.key_gen(seed);
  var pk = sk.get_g1();
  
  var message = Uint8Array.from([1,2,3,4,5]);
  var signature = BLS.AugSchemeMPL.sign(sk, message);
  
  let ok = BLS.AugSchemeMPL.verify(pk, message, signature);
  console.log(ok); // true

Serializing keys and signatures to bytes

  var skBytes = sk.serialize();
  var pkBytes = pk.serialize();
  var signatureBytes = signature.serialize();
  
  console.log(BLS.Util.hex_str(skBytes));
  console.log(BLS.Util.hex_str(pkBytes));
  console.log(BLS.Util.hex_str(signatureBytes));
  

Loading keys and signatures from bytes

  var skc = BLS.PrivateKey.from_bytes(skBytes, false);
  var pk = BLS.G1Element.from_bytes(pkBytes);

  var signature = BLS.G2Element.from_bytes(signatureBytes);

Create aggregate signatures

  // Generate some more private keys
  seed[0] = 1;
  var sk1 = BLS.AugSchemeMPL.key_gen(seed);
  seed[0] = 2;
  var sk2 = BLS.AugSchemeMPL.key_gen(seed);
  var message2 = Uint8Array.from([1,2,3,4,5,6,7]);
  
  // Generate first sig
  var pk1 = sk1.get_g1();
  var sig1 = BLS.AugSchemeMPL.sign(sk1, message);
  
  // Generate second sig
  var pk2 = sk2.get_g1();
  var sig2 = BLS.AugSchemeMPL.sign(sk2, message2);
  
  // Signatures can be non-interactively combined by anyone
  var aggSig = BLS.AugSchemeMPL.aggregate([sig1, sig2]);
  
  ok = BLS.AugSchemeMPL.aggregate_verify([pk1, pk2], [message, message2], aggSig);
  console.log(ok); // true
  

Arbitrary trees of aggregates

  seed[0] = 3;
  var sk3 = BLS.AugSchemeMPL.key_gen(seed);
  var pk3 = sk3.get_g1();
  var message3 = Uint8Array.from([100, 2, 254, 88, 90, 45, 23]);
  var sig3 = BLS.AugSchemeMPL.sign(sk3, message3);
  
  var aggSigFinal = BLS.AugSchemeMPL.aggregate([aggSig, sig3]);
  ok = BLS.AugSchemeMPL.aggregate_verify([pk1, pk2, pk3], [message, message2, message3], aggSigFinal);
  console.log(ok); // true

Very fast verification with Proof of Possession scheme

  // If the same message is signed, you can use Proof of Posession (PopScheme) for efficiency
  // A proof of possession MUST be passed around with the PK to ensure security.
  var popSig1 = BLS.PopSchemeMPL.sign(sk1, message);
  var popSig2 = BLS.PopSchemeMPL.sign(sk2, message);
  var popSig3 = BLS.PopSchemeMPL.sign(sk3, message);
  var pop1 = BLS.PopSchemeMPL.pop_prove(sk1);
  var pop2 = BLS.PopSchemeMPL.pop_prove(sk2);
  var pop3 = BLS.PopSchemeMPL.pop_prove(sk3);
  
  ok = BLS.PopSchemeMPL.pop_verify(pk1, pop1);
  console.log(ok); // true
  ok = BLS.PopSchemeMPL.pop_verify(pk2, pop2);
  console.log(ok); // true
  ok = BLS.PopSchemeMPL.pop_verify(pk3, pop3);
  console.log(ok); // true
  
  var popSigAgg = BLS.PopSchemeMPL.aggregate([popSig1, popSig2, popSig3]);
  ok = BLS.PopSchemeMPL.fast_aggregate_verify([pk1, pk2, pk3], message, popSigAgg);
  console.log(ok); // true
  
  // Aggregate public key, indistinguishable from a single public key
  var popAggPk = pk1.add(pk2).add(pk3);
  ok = BLS.PopSchemeMPL.verify(popAggPk, message, popSigAgg);
  console.log(ok); // true
  
  // Aggregate private keys
  var aggSk = BLS.PrivateKey.aggregate([sk1, sk2, sk3]);
  ok = (BLS.PopSchemeMPL.sign(aggSk, message).equal_to(popSigAgg));
  console.log(ok); // true

HD keys using EIP-2333

  // You can derive 'child' keys from any key, to create arbitrary trees. 4 byte indeces are used.
  // Hardened (more secure, but no parent pk -> child pk)
  var masterSk = BLS.AugSchemeMPL.key_gen(seed);
  var child = BLS.AugSchemeMPL.derive_child_sk(masterSk, 152);
  var grandChild = BLS.AugSchemeMPL.derive_child_sk(child, 952);
  
  // Unhardened (less secure, but can go from parent pk -> child pk), BIP32 style
  var masterPk = masterSk.get_g1();
  var childU = BLS.AugSchemeMPL.derive_child_sk_unhardened(masterSk, 22);
  var grandchildU = BLS.AugSchemeMPL.derive_child_sk_unhardened(childU, 0);
  
  var childUPk = BLS.AugSchemeMPL.derive_child_pk_unhardened(masterPk, 22);
  var grandchildUPk = BLS.AugSchemeMPL.derive_child_pk_unhardened(childUPk, 0);
  
  ok = (grandchildUPk.equal_to(grandchildU.get_g1()));
  console.log(ok); // true

Please refer to the library's typings for detailed API information. Use cases can be found in the original lib's readme.

Important note on usage: Since this library is a WebAssembly port of the c++ library, JavaScript's automatic memory management isn't available. Please, delete all objects manually if they are not needed anymore by calling the delete method on them, as shown in the example below.

  sk.delete();
  // ...
  pk.delete();
  // ...
  sig1.delete();
  // ...

Build

Building requires Node.js (with npm) and Emscripten to be installed. The build process is the same as for the c++ lib, with one additional step: pass the Emscripten toolchain file as an option to CMake. From the project root directory, run:

#git submodule update --init --recursive
mkdir js_build
cd js_build
cmake ../ -DCMAKE_TOOLCHAIN_FILE={path_to_your_emscripten_installation}/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
cmake --build . --

Run the build after any changes to the library, including readme and tests, as the library will be deployed from the build directory, and the build system copies all the files from the source dir.

Run tests

Tests are run in node.js and Firefox, therefore you need to install node.js and Firefox. To run tests, build the library, then go to the js_bindings folder in the build directory and run

npm test